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What are the G1 checkpoints?
- cell size is adequate
- nutrients are sufficient
- social signals are present
- DNA is undamaged
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What are the G2 checkpoints?
- chromosomes have replicated successfully
- DNA is undamaged
- activated MPF is present
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What are the Metaphase checkpoints?
all chromosomes are attached to mitotic spindle apparatus
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What is P53?
Tumor Suppressor
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What is PDGF?
Platelet Derived Growth Factor:
- Signal for cell division
- promotes wound healing
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Cancerous cells have two types of defects:
- defects that make proteins required for cell growth active when they shouldn't be.
- defects that prevent tumor suppressor genes from shutting downt the cell cycle.
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What is Rb protein?
a tumor suppressor gene, binds to E2F and inactivates it
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What happens if the sister chromatids of one chromosome fail to separate at anaphase?
One daughter cell receives too few chromosomes; the other receives a replicated chromosome.
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The Genetic Code has 4 important properties:
- Redundant - all amino acids coded by more than one codon
- Unambiguous - a single codon never codes for more than one amino acid
- Nearly Universal - All codons specify the same amino acids in all organisms
- Conservative - The first two bases in codons that specify the same amino acid, are always identical.
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RNA and DNA is always synthesized in the ___________ direction.
5' to 3'
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Which mutation changes nucleotide, but does not change amino acid specified by codon?
Silent
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Which mutation changes nucleotide that changes amino acid specified by a codon?
Missense
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Which mutation changes a nucleotide that results in early stop codon?
Nonsense
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Which mutation is defined by an addition or deletion of a nucleotide?
Frameshift
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When segments become flipped and rejoin, it is known as _______________.
Inversion
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When segments become attached to a different chromosome, it is known as _________________.
Translocation
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What are two exceptions to Central Dogma?
- Many genes code for RNA molecules that do not function as mRNA's - they are not translated into proteins.
- In some cases, info flows from RNA back to DNA.
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How many amino acids are represented in the genetic code by just one codon?
2 : Methionine and Tryptophan
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How many different amino acids would be found in a polypeptide made from translation of an RNA containing only cytosines (C) and adenines (A) in random order?
8 is the number of POSSIBLE codons, but only 6 are different.
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What is the most common number of codons that specifies a single amino acid?
two
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What is a tetrad?
4 chromatids from homologous chromosomes
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Meiosis - What happens in Interphase?
Chromosomes replicate in parent cell, in uncondensed state, forming sister chromatids.
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Meiosis - What happens in Early Prophase I?
- chromosomes condense
- nuclear envelope breaks up
- spindle apparatus forms
- synapsis of homologous chromosomes.
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Meiosis - What happens in Late Prophase I?
Crossing over of non-sister chromatids
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Meiosis - what is Chiasma?
an x shaped structure caused by each crossover
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Meiosis - What happens in Metaphase I?
Migration of tetrads to metaphase plate is complete
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Meiosis - What happens in Anaphase I?
Homologs separate and begin moving to opposite sides of cell
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Meiosis - What happens in Telophase I and Cytokinesis?
- Chromosomes move to opposite sides of cell
- then cell divides
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Meiosis - What happens in Prophase II?
- There is no interphase between I and II.
- Spindle apparatus forms.
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Meiosis - What happens in Methaphase II?
Chromosomes line up at the middle of the cell (metaphase plate)
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Meiosis - What happens in Anaphase II?
Sister chromatids separate, begin moving to opposite sides of cell
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Meiosis - What happens in Telophase II and Cytokinesis?
- Chromosomes move to opposite sides of cell
- then cell divides
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What is crossing over?
- The process of chromosome exchange.
- Takes place during Late Prophase I.
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Mitosis - What happens in Interphase?
- After chromosome replication, each chromosome is composed of two sister chromatids.
- Chromosomes have replicated.
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Mitosis - What happens in Prophase?
- Chromsomes condense
- Spindle apparates begins to form
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Mitosis - What happens in Prometaphase?
- Nuclear envelope breaks down
- Kinetochore microtubues contact chromosomes at kinetochore
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Mitosis - What happens in Metaphase?
Chromosomes complete migration to middle of cell.
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Mitosis - What happens in Anaphase?
- Sister chromatids separate
- Chromosomes are pulled to opposite poles of the cell
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Mitosis - What happens in Telophase?
- The nuclear envelope re-forms
- Spindle apparatus disintegrates
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What event of Meiosis makes meiosis a reduction division, unlike mitosis?
During Anaphase I, homologs (not sister chromatids, as in mitosis) are separated, making the cel products of meiosis I haploid.
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What are homologous chromosomes?
Chromosomes that are similar in their size, shape, and gene content.
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What is a tetrad?
A group of four chromatids produced when homologs synapse.
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Meiosis II is similar to which process?
Mitosis in haploid cells.
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What is synapsis?
The process of homologous chromosomes pairs coming together.
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What is the end result of meiosis and subsequent fertilization of gametes?
an offspring with a chromosome complement unlike that of either parent
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What information can not be obtained from an individual's karyotype?
- The sequence of bases of a particular gene
- Karyotype is the study of the number and types of chromosomes present.
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What is the composition of a tetrad at the beginning of prophase I?
- One pair of homologous chromosomes
- The tetrad is made up of two chromosomes, not four.
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Name Five Essential Developmental Processes:
- Cell Proliferation
- Programmed cell death
- Cell movement or differential expansion
- Cell differentiation
- Cel-cell interactions
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What is totipotent?
- (all powerful) cells that can de-differentiate and then differentiate to from neded cells.
- Only occur in plants.
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What is responsible for differentiation?
- Transcriptional control
- In eukaryotes, transcription is controlled primarily by the presence of regulatory transcription factors.
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Cells become specialized because they _________________ different genes.
express
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Do Meristematic cells and stem cells differentiate?
No, but they continue proliferating throughout life.
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What is homeosis?
- (Like-Condition). Homeosis occurs when cells get incorrect information about where they are in the body.
- Replacement of one structure by another structure
- Structure develops in the wrong location
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What are homeotic genes?
- homeotic genes regulate effector genes
- homeotic gene products identify each segment's structural role
- hox genes are homeotic genes
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What is the function of stem cells in adult mammals?
They produce cells that differentiate to replace dead or damaged cells.
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What is a homeotic mutant?
An individual with a structure located in the wrong place.
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Gastrulation is marked by which of the four essential developmental processes?
cell movement
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What process marks the initiation of cell differentiation?
Cells initiate differential gene expression.
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Which of the following processes is the most important level of control over gene expression?
transcriptional regulation
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What similarities are found when comparing the homeotic genes of Drosophilaand the Hox genes of the mouse?
- genes are expressed in a similar head-to-tail pattern
- they are in the same order on the chromosome
- mutation of the genes in either organism causes homeosis.
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What is central dogma?
- summarizes the flow of information in cells.
- DNA (info storage) to RNA (info carrier) to proteins (active cell machinery)
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Name 2 examples of Ectoderm Layer:
- Epidermis of Skin
- Nervous System
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Name 2 examples of Mesoderm Layer:
- Muscular System
- Reproductive System
- Skeletal System
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Name 2 exaples of Endoderm Layer:
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